This invention relates to a method of immobilization enzymes and, more particularly, to a method for enzyme immobilization comprising the steps of treating microorganic cells or microorganic cells which have undergone various forms of treatments with a reagent having at least two functional groups and allowing an enzyme to react with resultant microorganic cells which have functional groups in a free state.
Immobilization (insolubilization) of enzymes has been attracting keen attention as a means for enabling enzyme reactions which have invariably been carried out in a batch operation to be accomplished in a continuous operation.
For example, a method whereby an enzyme is rendered insoluble in water by polymerizing the enzyme in the presence of a bifunctional reagent serving as an agent to bridge the enzyme molecules is disclosed in A. Schejter, A. Bar-Eli, Arch. Biochem. Biophys. Vol. 136, page 325 (1970) and a method whereby an enzyme is bonded to a water-insoluble carrier having an active group such as polyacrolein or polyurethane so as to produce an insolubilized enzyme has already been disclosed to the art.
The methods which have heretofore been disclosed have various disadvantages. For example, they entail high costs for the preparation of the insolubilized enzymes, fail to provide insolubilized enzymes with sufficiently high enzyme activity, allow enzymes to flow out of position in use because of insufficient immobilization, and necessitate development of different techniques to suit the immobilization of particular kinds of enzymes. These methods, therefore, have found very few commercial applications.
I have previously suggested a method whereby glucose isomerase-containing cells are subjected to heat treatment at 55.degree. - 90.degree.C to immobilize glucose isomerase within the cells. Since this method can economically produce the immobilized enzyme, it has already been adopted for commercial production of fructose from glucose. However, since no economical method has yet been made available for the immobilization of glucoamylase, it has heretofore been impossible to manufacture glucose continuously from starch (which term, for the purpose of the present specification, encompasses also liquefied starch, dextrin and the like) or produce fructose directly from starch by combining with the action of glucoamylase with that of glucose isomerase.
A primary object of the present invention is to provide a method of facilitating immobilization of enzymes on microorganic cells such as molds and actinomycetecells or products of treatments thereof.